Immunologic reactivity towards tumor-associated antigens has been demonstrated in both choroidal melanoma and retinoblastoma patients, however the specificity and biologic importance of these immune responses remain undetermined. There are a myriad of antigens on tumor cell surfaces; using antibodies raised in heterologous hosts, it is extremely difficult to determine whether tumor-specific antigens or antigenic components shared with normal tissue are responsible for the immunologic reactivity observed in ocular tumor patients. Hybridoma methodology can be used to produce a family of monoclonal antibodies; with appropriate screening, antibodies with reactivity towards relevant antigens can be selected. In some animal and human tumors, including systemic melanoma, hybridoma antibodies specific for both immunizing and allogeneic tumor-specific antigens have been produced. We will determine whether tumor-specific antigens occur in retinoblastoma and choroidal melanoma using hybridoma methodology and appropriate immunologic assays (MHA, cytotoxity, IA, RAI, etc.) Purified tumor antigens can also be obtained by using these hybridoma antibodies as immunoabsorption columns. These antigens can be used in both in vitro immunodiagnostic assays (LMI) as well as to help elucidate the nature of the antigenic component of immune complexe observed in ocular tumor patients. Appropriate tumor-specific hybridoma antibodies can be radiolabeled, and used to diagnose and localize ocular tumors by external, non-invasive, scintigraphy. This type of procedure would obviate the need for invasive diagnostic studies such as 32p testing, and might also be a more sensitive test for the diagnosis of early metastases. Tumor-specific antibodies could also be useful as immunotherapeutic agents; by coupling them with potent anticancer drugs as a form of chemotherapy, they may also be effacious in the treatment of metastatic ocular tumors.